The vertical or horizontal emissive laser line beam by such laser line beam emitting apparatus may be used as a vertical or horizontal reference line passing objects such as a ceiling, a floor and walls or front, side and back walls in constructs.
This laser beam, which is generally an elliptical beam with a transverse section as its feature, is passed into a horizontal or vertical axial cylindrical rod lens through a collimator lens and becomes a vertically or horizontally broadened beam.
The foregoing laser line beam emitting apparatus has, as production of the vertical or horizontal emissive laser line beam, use of a laser emitter, which is a component making up a laser unit held to a laser unit holder held from a gimbals mechanism, therein. The laser unit holder may be maintained in a desired position without tilt with respect to the position so that emission of adequate vertical or horizontal laser beam flux may be performed.
The interior of the laser line beam emitting apparatus is provided with a laser beam source comprised of a semiconductor laser for emission of laser line beam and optical or precisely processing instruments such as cylindrical rod lens and gimbals mechanism, that are assembled therein. Therefor, the laser line beam emitting apparatus has a main covering so that it is airtight for protection of the interior from enterer of dust. Such laser line beam emitting apparatus has outlet(s) formed at predetermined position(s) of the main covering. The outlet(s) permit transmission of respective laser beam flux and are provided with respective dust protective coverings for protection from invading dust. The dust protective covering comprises a transparent glass or synthetic resin plate or film and so on.
The following gives a summarized description of a conventional laser line beam emitting apparatus, with reference to FIGS. 3 to 5. In FIG. 3, an underside base board 10 has three legs 12 mounted thereto such that the base board may be maintained in an approximate horizontal position through the legs. The upside base board 10 has a suitable number of columns 14 vertically stood thereon, each of the columns 14 has a gimbals mechanism 15 mounted at its top end, and a laser unit holder 24 is hung down from the gimbals mechanism. The laser unit holder 24 may have free swings to all directions.
The laser unit holder 24 has a first laser unit 30 tilted upward and mounted at its top end for emission of a vertical beam, a second laser unit 40 mounted in horizontal arrangement at a position below the gimbals mechanism 15 for emission of a horizontal beam, and a third laser unit 50 mounted at its lowermost with orientation to the undernearth for emission of spot(s) on a floor.
The first laser unit 30 for emission of a vertical beam comprises a laser beam source 31, a collimator lens 32 for collimated formation of the emissive laser beam from the laser beam source 31, and a cylindrical rod lens 33 for expansion of the collimated emissive beam only in vertical directions. The second laser unit 40 for emission of a horizontal beam also is of the approximate same construction, which comprises a laser beam source 41, a collimator lens 42 for parallel formation of the emissive laser beam from the laser beam source 31, and a cylindrical rod lens 43 for expansion of the paralleled emissive beam only in a horizontal direction. The third laser unit 50 for emission of spot(s) on a floor comprises a laser beam source 51, and a collimator lens 52 for collimated formation of the emissive laser beam from the laser beam source. Each of the laser units 30, 40, 50 is assembled into a cylindrical mirror. Each of the laser beam source 31, 41, 51 comprises, for example, a semiconductor laser.
The laser unit holder 24 is hung down through the gimbals mechanism 15 so that it may have an approximate vertical position. At the position electric power is applied to the laser beam sources 31, 41, 51 of respective first, second and third laser units 30, 40, 50, and then such laser beam flux are emitted out from respective laser units 30, 40, 50. The first laser unit 30 performs emission of a vertically broadened laser beam flux, which is drawn on its object(s) such as construct's wall(s) with drawing of a straight line on a floor and a ceiling that are continued to the corresponding walls, through respective transverse section, at the beam path. The second laser unit 40 performs emission of a horizontally broadened laser beam, which is drawn on its object(s) such as construct's walls at the beam path. The third laser unit 50 performs emission of collimated laser beam flux to the undernearth with drawing of laser spots on its objects such as a construct's floor on which the laser beams are formed at reference markings as indicated thereon.
Such laser line beam emitting apparatus has a main covering 60 provided for covering over the foregoing components. A vertical longitudinal outlet 61 is formed in the main covering 60 so as to avoid interruption of the vertically broadened, emitted laser beam flux from the laser unit 30, while a horizontal longitudinal outlet 62 is formed in the main covering 60 so as to avoid interruption of the horizontally broadened, emitted laser beam flux from the laser unit 40. The foregoing dust protective covering is provided into each of the outlets 61, 62.
FIG. 4 shows an example of provision of a dust protective covering according to the conventional laser line beam emitting apparatus. In FIG. 4, a dust protective covering 63, which is formed of a flat transparent plate, is fitted in the outlet formed at the ceiling of the main covering 60 of the laser line beam emitting apparatus. In addition, a dust protective covering 64, which is formed of a flat transparent plate, is fitted in the outlet formed at the front of the main covering 60 nearer to the ceiling thereof. Any of the dust protective coverings 63, 64 permit passage of the vertically broadened laser beam from the laser unit 30.
From the foregoing, each of the dust protective coverings 63, 64 of the laser line beam emitting apparatus comprises a flat transparent material formed of glass, synthetic resin or film and so on. Since each of them has an inner surface parallel with the transverse section of the emitted laser beam, the reflected beam therefrom returns to the interior of the apparatus, and thus does not cause the emitted objects to be subject to, for example, produced ghost. However, when the laser beam flux with formation of a vertical or horizontal straight reference line on the objects are transmitted onto the dust protective coverings 63, 64, most of the section of the laser beam flux are not parallel to the inner surfaces of respective dust protective coverings 63, 64, because of that the laser beam flux is broadened through the cylindrical rod lens. Hence, most of the section of the broadened laser beam flux through the cylindrical rod lens will be directed diagonally with respect to the inner surfaces of respective dust protective coverings 63, 64.
For the reason, as shown by the numeral reference 65 in FIG. 5, for example, a part of the diagonally directed laser beam with respect to the inner surface of the dust protective covering 63 are reflected from the inner surface of the dust protective covering 63, and then go toward another dust protective covering 64 for passage through the dust protective covering 64 and the emission onto the objects. This produces a ghost formed by the laser beam as represented by the numeral reference 65, whereby both of the original correct reference and forgeable lines are emitted, which are misleading.